The world egg, cosmic egg or mundane egg is a mythological motif found in the creation myths of many cultures and civilizations. Typically, the world egg is a beginning of some sort, and the universe or some primordial being comes into existence by "hatching" from the egg, sometimes lain on the waters of the Earth.
One of the earliest ideas of "egg-shaped cosmos" comes from some of the Sanskrit scriptures. The Sanskrit term for it is Brahmanda (ब्रह्माण्ड) which is derived from two words- 'Brahm' (ब्रह्म) means 'cosmos' or 'expanding' and 'anda' (अण्ड) means 'egg'. Certain Puranas such as the Brahmanda Purana speak of this in detail.
The Rig Veda (RV 10.121) uses a similar name for the source of the universe: Hiranyagarbha (हिरण्यगर्भ) which literally means "golden fetus" or "golden womb". The Upanishads elaborate that the Hiranyagarbha floated around in emptiness for a while, and then broke into two halves which formed Dyaus (Heaven) and Prithvi (Earth). The Rig Veda has a similar coded description of the division of the universe in its early stages.
The Orphic Egg in the ancient Greek Orphic tradition is the cosmic egg from which hatched the primordial hermaphroditic deity Phanes/Protogonus (variously equated also with Zeus, Pan, Metis, Eros, Erikepaios and Bromius) who in turn created the other gods. The egg is often depicted with a serpent wound around it.